2.0 Analysis 2.1 General This accident was a non-associated midair collision,(8) that is, the pilots involved were not intentionally flying in each other's vicinity, and neither knew that the other was there. Although regulations and procedures address right of way issues, they do not apply to non-associated collisions. A pilot cannot be expected to give way to another if he/she is not aware of the other. No evidence of mechanical defect with either aircraft was found. Accordingly, this analysis focuses on the operational issues of flight in a confined training area and the inherent limitations of the see-and-avoid principle. 2.2 Operational Circumstances In Canada, the see-and-avoid principle is used as the primary means of maintaining spacing between aircraft in visual meteorological conditions. Research shows that this principle is the least effective of the available mechanisms to keep aircraft apart because of the physiological limitations of the human eye and the motor-response systems. Accordingly, reliance on the see-and-avoid principle as the primary means of separation may be inadequate, particularly where the aircraft are close to head-on with high closure speeds. The flight profiles of both accident aircraft indicate that neither pilot saw the other aircraft in sufficient time to initiate effective and timely evasive action. The cockpit circumstances at the time of the accident are not entirely known. The Aircoupe pilot's attention was probably focused on orbiting and manoeuvring around the ultralight, whereas the attention of the Cessna pilots was likely focused on the training environment. Although this cannot be proven, it is a scenario to which most pilots can relate and underlines why constant vigilance is so important, especially in uncontrolled airspace. Consequently, the pilots' respective tasks limited their opportunity to detect each other. Research indicates that a pilot is eight times more likely to visually acquire another aircraft when alerted to its presence. Traffic advisories greatly assist pilots develop and maintain situational awareness (a mental picture of relevant traffic). Missing, incomplete, or inaccurate position reports from pilots, communication problems, frequency congestion, and pilot workload can introduce further inaccuracies when a pilot tries to use this information to recognize or resolve potential conflict. The Aircoupe is a low-wing aircraft with the pilot's seat over the wing. During the right bank in the turn, the left wing would have restricted the pilot's field of view to his left, the direction from which the Cessna approached. It may therefore have been physically impossible for the occupants of the Aircoupe to see the Cessna until just before the aircraft collided. From the perspective of the Cessna pilots, the Aircoupe would have been approaching from the front, right quadrant. The target image would have been a small profile view. The yellow Aircoupe may have blended with the variegated background, and no indication was found that the Aircoupe's landing light was on. Without a warning, the Cessna pilots may not have detected the Aircoupe. The Aircoupe would have appeared motionless to them for about 10 seconds because of their constant relative bearing, which commenced when the aircraft speeds and headings combined to establish the collision course. Canadian regulations require all pilots to maintain separation from other aircraft in flight so as not to create a risk of collision. To maintain this separation effectively, pilots must vigilantly scan for other air traffic. All pilots need to maintain a more assiduous lookout in training areas because training aircraft generally follow erratic flight paths and perform unpredictable manoeuvres. Effective lookout is degraded by the high workload and focus on training in the cockpit. The TC safety promotion pamphlet Take Five recommends that all pilots operating in the training area CYA 125 (T) monitor the aerodrome radio frequency of 123.5 MHz. The pamphlet also encourages pilots to provide position advisories. Had they followed these recommended communication procedures, the accident pilots would likely have improved their situational awareness and reduced the level of risk of collision. 3.0 Conclusions 3.1 Findings as to Causes and Contributing Factors Neither pilot saw the other aircraft in time to avoid the collision. The pilots were not in communication with each other and did not monitor the recommended frequency for CYA125(T). 3.2 Findings as to Risk Fading light conditions at sunset, background camouflage, aircraft design, and the inherent limitations of the human eye may preclude effective see-and-avoid separation of aircraft on a collision course. Neither accident aircraft had any additional technological equipment to detect conflicting aircraft, nor was such equipment required by existing regulation. 3.3 Other Findings The Cessna had its landing light on leading up to the accident. This light was an effective visual detection aid. The ultralight's flight path was consistent with normal operations and procedures in uncontrolled airspace. The Aircoupe's flight path was unusual in that it flew an orbit around the ultralight. The Cessna's flight path was consistent with normal operations and procedures in uncontrolled airspace. The Cessna's heading, speed, and attitude at collision indicate that the pilots did not see the Aircoupe before impact. It could not be determined if the occupants of the Aircoupe saw the Cessna immediately before impact. Nav Canada does not provide traffic conflict resolution in CYA 125 (T), nor is it required to by regulation or agreement. 4.0 Safety Action 4.1 Action Taken 4.1.1 Nav Canada Nav Canada provides all air traffic services in Canada. As a result of this accident and unrelated operational air traffic control incidents, Nav Canada identified a timely opportunity to present situational awareness and procedural education to local general aviation pilots, flying schools, and pleasure flyers. Nav Canada embarked on a series of situational awareness workshops in concert with Transport Canada (TC) System Safety and the TSB Pacific regional office. These workshops were open to all general aviation pilots in the lower mainland in British Columbia. Over three months, speakers from the three agencies presented several operational issues and situational awareness techniques at six workshops. Attendance at the workshops was high, with pilots of diverse background and experience. 4.1.2 Transport Canada In April 1999, before this occurrence, TC System Safety issued the Take Five safety promotion pamphlet in an attempt to reduce the risk of in-flight collision in CYA 125 (T). The pamphlet identifies traffic congestion in this area as a serious problem because of the dense mixture of ultralight, training, and transiting aircraft. The pamphlet highlights the requirement for a vigilant lookout in this area but also identifies that other precautions are necessary. The first counsel is that aircraft not participating in flight training operations avoid the area whenever possible. Secondly, the pamphlet advises that, since the training area contains an active ultralight field, all pilots operating in the area should monitor the aerodrome radio frequency of 123.5 MHz. In addition, the pamphlet encourages pilots to provide position advisories. Following this accident, TC System Safety participated in several of the situational awareness workshops conducted by Nav Canada. TC System Safety is planning to conduct similar workshops on a more regular basis. 4.1.3 Pacific Flying Club Shortly after the accident, the Pacific Flying Club fitted pulsing landing lights on all its aircraft to improve the conspicuity of their aircraft. The Pacific Flying Club also sponsored two Nav Canada situational awareness workshops.